<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        html, body {
            margin: 0;
            height: 100%;
        }

        canvas {
            display: block;
        }

    </style>
</head>
<body onload="draw();">

</body>
<script src="https://cdn.bootcss.com/three.js/91/three.min.js"></script>
<script src="js/PLYLoader.js"></script>
<script src="js/controls/OrbitControls.js"></script>
<script src="js/libs/tween.min.js"></script>
<script src="js/libs/stats.min.js"></script>
<script src="https://cdn.bootcss.com/dat-gui/0.7.1/dat.gui.min.js"></script>

<script>
    var renderer;

    function initRender() {
        renderer = new THREE.WebGLRenderer({antialias: true});
        renderer.setSize(window.innerWidth, window.innerHeight);
        //告诉渲染器需要阴影效果
        renderer.setClearColor(0xffffff);
        document.body.appendChild(renderer.domElement);
    }

    var camera;

    function initCamera() {
        camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
        camera.position.set(0, 0, 50);
        camera.lookAt(new THREE.Vector3(0, 0, 0));
    }

    var scene;

    function initScene() {
        scene = new THREE.Scene();
    }

    //初始化dat.GUI简化试验流程
    var gui;

    function initGui() {
        //声明一个保存需求修改的相关数据的对象
        gui = {};
        var datGui = new dat.GUI();
        //将设置属性添加到gui当中，gui.add(对象，属性，最小值，最大值）
    }

    var light;

    function initLight() {
        scene.add(new THREE.AmbientLight(0x444444));

        light = new THREE.PointLight(0xffffff);
        light.position.set(0, 50, 50);

        //告诉平行光需要开启阴影投射
        light.castShadow = true;

        scene.add(light);
    }

    function initModel() {

        //辅助工具
        var helper = new THREE.AxesHelper(50);
        scene.add(helper);

        var loader = new THREE.PLYLoader();
        loader.load("json/Lucy100k.ply", function (geometry) {

            //更新顶点的法向量
            geometry.computeVertexNormals();

            //创建纹理，并将模型添加到场景道中
            var material = new THREE.MeshStandardMaterial({color: 0x0055ff});
            var mesh = new THREE.Mesh(geometry, material);
            mesh.rotation.y = Math.PI;
            mesh.scale.set(0.02, 0.02, 0.02);
            scene.add(mesh);

            //保存一份默认的顶点信息
            var position = geometry.getAttribute("position").array;
            geometry.localPosition = [];
            for (var i = 0; i < position.length; i++) {
                geometry.localPosition.push(position[i]);
            }

            //初始化tween动画

            initTween(geometry);
        });
    }

    //添加tween动画
    var tween;

    function initTween(geometry) {
        var position = {y: 1};
        tween = new TWEEN.Tween(position).to({y: 0}, 5000);
        tween.easing(TWEEN.Easing.Sinusoidal.InOut);

        var tweenBack = new TWEEN.Tween(position).to({y: 1}, 5000);
        tweenBack.easing(TWEEN.Easing.Sinusoidal.InOut);

        tween.chain(tweenBack);
        tweenBack.chain(tween);

        var count = geometry.getAttribute("position").count;

        //获取一下模型的最矮处
        geometry.computeBoundingBox();
        var minY = geometry.boundingBox.min.y;

        var onUpdate = function () {
            var y = this.y;

            var arr = [];
            for (var i = 0; i < count; i++) {
                arr.push(geometry.localPosition[i * 3]);
                arr.push((geometry.localPosition[i * 3 + 1]-minY) * y);
                arr.push(geometry.localPosition[i * 3 + 2]);
            }

            geometry.getAttribute("position").array = new Float32Array(arr);

            geometry.getAttribute("position").needsUpdate = true;

        };

        tween.onUpdate(onUpdate);
        tweenBack.onUpdate(onUpdate);

        tween.start();
    }

    //初始化性能插件
    var stats;

    function initStats() {
        stats = new Stats();
        document.body.appendChild(stats.dom);
    }

    //用户交互插件 鼠标左键按住旋转，右键按住平移，滚轮缩放
    var controls;

    function initControls() {

        controls = new THREE.OrbitControls(camera, renderer.domElement);

        // 如果使用animate方法时，将此函数删除
        //controls.addEventListener( 'change', render );
        // 使动画循环使用时阻尼或自转 意思是否有惯性
        controls.enableDamping = true;
        //动态阻尼系数 就是鼠标拖拽旋转灵敏度
        //controls.dampingFactor = 0.25;
        //是否可以缩放
        controls.enableZoom = true;
        //是否自动旋转
        controls.autoRotate = false;
        controls.autoRotateSpeed = 0.5;
        //设置相机距离原点的最远距离
        controls.minDistance = 1;
        //设置相机距离原点的最远距离
        controls.maxDistance = 200;
        //是否开启右键拖拽
        controls.enablePan = true;
    }

    function render() {

        TWEEN.update();

        renderer.render(scene, camera);
    }

    //窗口变动触发的函数
    function onWindowResize() {

        camera.aspect = window.innerWidth / window.innerHeight;
        camera.updateProjectionMatrix();
        render();
        renderer.setSize(window.innerWidth, window.innerHeight);

    }

    function animate() {
        //更新控制器
        render();

        //更新性能插件
        stats.update();

        controls.update();

        requestAnimationFrame(animate);
    }

    function draw() {
        initGui();
        initRender();
        initScene();
        initCamera();
        initLight();
        initModel();
        initControls();
        initStats();

        animate();
        window.onresize = onWindowResize;
    }
</script>
</html>